User Manual

RTH and Navigation
The navigation (RTH) has only one PID control, the desired speed is directly calculated from the
distance to the target and the defined speed constrains. The NAV_P, NAV_I and NAV_D
parameters have the same functions as the POSHOLD_RATE.
Getting ready for flight
Clearing the EEPROM
It’s not a necessary step, but some people ran into weird problems after uploading the code. The
root cause of these problems was a corrupted EEPROM content. To avoid such a problem, it’s
recommended to erase the EEPROM content before upload the new code at the first time.
Start your Arduino IDE, Select File->Examples->EEPROM->eeprom_clear
Upload the sketch and wait. When the status led is on, it’s finished. Now you can compile and
upload the new code.
Compiling the code
There are some extra steps are needed to get the code compiled in the arduino IDE. The GPS
functions are using two libraries for PI and PID controllers. These libraries are in the Arduino-
PID-libs folder and you have to copy them into the libraries folder in your arduino folder. If you
planning to use i2c_gps, then an extra step is needed. The i2c communication library that comes
with arduino needs a patch. You have to take twi.c and twi.h from the Arduino-twi-lib-patch and
copy them to the libraries\wire\utilities folder.
First test and tuning
Pre flight tests
Before testing any GPS functions make sure that your copter perfectly working in level mode
and your mag is precise. Mag should not be influenced by motor power wires. If necessary try to
move your mag away from the power wires. Always make a ground test with a new copter, tie it
down, open throttle and check MAG graph in GUI, it should not change when you increase
throttle.
During the initial GPS flights I recommend to use HEADFREE mode, in case you lost
orientation, or something goes wrong. (Thanks to HEADFREE mode, during the development I
was able to bring home my tri, which continuously rotated.)
For GPS functions, you will also need a good GPS reception, and a solid GPS lock. Your GPS
receiver must see at least 5 satellites for acceptable precision. There are two visual indicators
that show that your GPS acquired lock.
If copter is disarmed, when a solid lock is achieved, the Flight Controller’s status led will start
blink.